Problem: In this problem your goal is to sort an array consisting of n integers in at most n swaps. For the given array find the sequence of swaps that makes the array sorted in the non-descending order. Swaps are performed consecutively, one after another.

Note that in this problem you do not have to minimize the number of swaps — your task is to find any sequence that is no longer than n.

Input

The first line of the input contains integer n (1 ≤ n ≤ 3000) — the number of array elements. The second line contains elements of array: a0, a1, ..., an - 1 ( - 109 ≤ ai ≤ 109), where ai is the i-th element of the array. The elements are numerated from 0 to n - 1 from left to right. Some integers may appear in the array more than once.

Output

In the first line print k (0 ≤ k ≤ n) — the number of swaps. Next k lines must contain the descriptions of the k swaps, one per line. Each swap should be printed as a pair of integers i, j (0 ≤ i, j ≤ n - 1), representing the swap of elements ai and aj. You can print indices in the pairs in any order. The swaps are performed in the order they appear in the output, from the first to the last. It is allowed to print i = j and swap the same pair of elements multiple times.

If there are multiple answers, print any of them. It is guaranteed that at least one answer exists.

Examples

Input

5
5 2 5 1 4


Output

2
0 3
4 2


Input

6
10 20 20 40 60 60


Output

0


Input

2
101 100


Output

1
0 1

Solution (in JAVA):

Solution:
import java.util.*;
import java.io.*;

public class A2oj2 {

    static FastReader sc;
    static PrintWriter out;
    static int mod = 1000000007;

    public static void main(String[] args) throws IOException {
        if (System.getProperty("ONLINE_JUDGE") == null) {
            File f1 = new File("input.txt");
            File f2 = new File("output.txt");
            Reader r = new FileReader(f1);
            sc = new FastReader(r);
            out = new PrintWriter(f2);
            double prev = System.currentTimeMillis();
            solve();
            out.println("\n\nExecuted in : " + ((System.currentTimeMillis() - prev) / 1e3) + " sec");
        } else {
            sc = new FastReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            solve();
        }
        out.flush();
        out.close();
    }

    static void solve() {
        // int t = sc.nextInt();
        // StringBuilder ans = new StringBuilder("");
        // while (t-- > 0) {

        // }
        // out.println(ans);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++)
            arr[i] = sc.nextInt();
        ArrayList<Pair> apr = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            // out.println("Here");
            int ind = i;
            for (int j = i + 1; j < n; j++) {
                if (arr[ind] > arr[j]) {
                    ind = j;
                }
            }
            if (ind != i) {
                apr.add(new Pair(i, ind));
                int tmp = arr[ind];
                arr[ind] = arr[i];
                arr[i] = tmp;
            }
        }
        out.println(apr.size());
        for (Pair e : apr) {
            out.println(e.x + " " + e.y);
        }
    }

    static int gcd(int a, int b) {
        if (b == 0)
            return a;
        else
            return gcd(b, a % b);
    }

    public static int digitsCount(long x) {
        return (int) Math.floor(Math.log10(x)) + 1;
    }

    public static boolean isPowerTwo(long n) {
        return (n & n - 1) == 0;
    }

    static void sieve(boolean[] prime, int n) { // Sieve Of Eratosthenes
        for (int i = 1; i <= n; i++) {
            prime[i] = true;
        }
        for (int i = 2; i * i <= n; i++) {
            if (prime[i]) {
                for (int j = 2; i * j <= n; j++) {
                    prime[i * j] = false;
                }
            }
        }
    }

    static void fillGraph(ArrayList<ArrayList<Integer>> adj) {
        int n = sc.nextInt(), m = sc.nextInt();
        for (int i = 0; i < n + 1; i++) {
            adj.add(new ArrayList<Integer>());
        }
        for (int i = 1; i <= m; i++) {
            int x = sc.nextInt(), y = sc.nextInt();
            adj.get(x).add(y);
            adj.get(y).add(x);
        }
    }

    static void dfs(ArrayList<ArrayList<Integer>> adj, boolean[] visited, int v) {
        visited[v] = true;
        out.print(v + " ");
        for (Integer i : adj.get(v)) {
            if (!visited[i])
                dfs(adj, visited, i);
        }
    }

    static void bfs(ArrayList<ArrayList<Integer>> adj, int V, int s) {
        boolean[] visited = new boolean[V];
        Queue<Integer> q = new LinkedList<>();
        visited[s] = true;
        q.add(s);
        while (!q.isEmpty()) {
            s = q.poll();
            out.print(s + " ");
            for (Integer i : adj.get(s)) {
                if (!visited[i]) {
                    visited[i] = true;
                    q.add(i);
                }
            }
        }
    }

    int fib(int n) { // n-th Fibonacci Number
        int a = 0, b = 1, c, i;
        if (n == 0)
            return a;
        for (i = 2; i <= n; i++) {
            c = a + b;
            a = b;
            b = c;
        }
        return b;
    }

    static long nCr(int n, int r) { // Combinations
        if (n < r)
            return 0;
        if (r > n - r) { // because nCr(n, r) == nCr(n, n - r)
            r = n - r;
        }
        long ans = 1L;
        for (int i = 0; i < r; i++) {
            ans *= (n - i);
            ans /= (i + 1);
        }
        return ans;
    }

    static long catalan(int n) { // n-th Catalan Number
        long c = nCr(2 * n, n);
        return c / (n + 1);
    }

    static class Pair implements Comparable<Pair> { // Pair Class
        long x;
        long y;

        public Pair(int x, int y) {
            this.x = x;
            this.y = y;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (!(o instanceof Pair)) {
                return false;
            }

            Pair pair = (Pair) o;

            if (x != pair.x) {
                return false;
            }
            if (y != pair.y) {
                return false;
            }

            return true;
        }

        @Override
        public int hashCode() {
            long result = x;
            result = 31 * result + y;
            return (int) result;
        }

        @Override
        public int compareTo(Pair o) {
            return (int) (this.x - o.x);
        }
    }

    static class Trip { // Triplet Class
        long x;
        long y;
        long z;

        Trip(long x, long y, long z) {
            this.x = x;
            this.y = y;
            this.z = z;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (!(o instanceof Trip)) {
                return false;
            }

            Trip trip = (Trip) o;

            if (x != trip.x) {
                return false;
            }
            if (y != trip.y) {
                return false;
            }
            if (z != trip.z) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            long result = 62 * x + 31 * y + z;
            return (int) result;
        }
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader(Reader r) {
            br = new BufferedReader(r);
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}